July 3 (UPI) -- North Korea has enough fissile material for about 10-20 nuclear warheads, according to the Stockholm International Peace Research Institute.
Quoting figures from January 2017, the Sweden-based think tank stated in a report issued Monday that North Korea is "estimated to have enough fissile material for approximately 10–20 nuclear warheads, an increase on the estimates for previous years."
The report added North Korea "carried out an unprecedented number of flight tests of different missile systems in 2016 with mixed results."
But SIPRI stated it is unlikely North Korea has developed a sufficiently compact nuclear warhead capable of reaching the continental United States.
"North Korea appears to have made technical progress in its military nuclear and ballistic missile programs and may have built up to 20 nuclear warheads," the report stated. "However, there is no open-source evidence that North Korea has produced nuclear warheads that can be carried on ballistic missiles."
The report also noted North Korea is increasing its reserves of weapons-grade plutonium annually, and advancing the development of intercontinental ballistic missiles.
But North Korea's ICBMs are still under development, according to SIPRI's analysis of the recent North Korea military parade on April 15.
Global nuclear weapons trends indicate the total number of nuclear warheads is on the decline.
The United States, Russia, the United Kingdom, France, China, India, Pakistan, Israel and North Korea possess a total of about 14,935 weapons in January 2017, down from 15,395 in early 2016.
Reductions, however, do not imply a decrease in spending.
"The data show that while the overall number of nuclear weapons in the world continues to decline, all of the nuclear weapon-possessing states are in the process of modernizing their nuclear arsenals and will not be prepared to give them up for the foreseeable future," the report states.
The United States could spend up to $1 trillion over the next three decades for nuclear weapons modernization, the report states.
Russia and the United States account for more than 90 percent of all nuclear weapons.